A wireless terminal device which exists in a wireless communication system selects one of a plurality of wireless base stations to relay communication, and communicates via the wireless base station. Generally, as described in reference 1 (Japanese Patent Laid-Open No. 3-268697), a wireless terminal device which is going to connect to another wireless terminal device measures the received field strength and the like of a radio signal from one or a plurality of wireless base stations located around the wireless terminal device, and selects a wireless base station based on the measurement result. For example, a wireless base station which outputs a radio signal with a highest received field strength is selected.
When using the method of selecting a wireless base station based on the received field strength, the wireless terminal device monitors radio signals from the wireless base station even during connection with the selected wireless base station. Upon detecting that the received field strength has fallen below a predetermined value, the wireless terminal device starts processing of searching for a switch destination wireless base station. Upon detecting a radio signal having a received field strength higher than that of the radio signal from the currently connected wireless base station, the wireless terminal device switches the connection destination wireless base station from the currently connected wireless base station to the wireless base station which output the radio signal with a higher received field strength.
There also exists a method described in Reference 2 (Japanese Patent Laid-Open No. 10-98759), in which a wireless terminal device includes a database that stores information representing coverage areas in correspondence with base stations, and a self device position detection unit such as a GPS (Global Positioning System) receiver so as to select a wireless base station that covers the self device position detected by the self device position detection unit.
Note that reference 3 (Japanese Patent Laid-Open No. 2003-110579) describes a method of, in a system including an apparatus for implementing a service requested by a wireless terminal device via wireless communication, causing the wireless terminal device to receive, using a near field communication scheme, device identification information from the apparatus for implementing the service. In addition, reference 4 (Japanese Patent Laid-Open No. 2006-238343) describes a method of, in a system which causes a plurality of wireless terminal devices to communicate via wireless access points, causing the wireless terminal devices to receive, using a near field communication scheme, predetermined information from the wireless access points.